1. Field of the Invention
This invention relates to a developer carrying member and a developing apparatus.
2. Description of the Related Art
In recent years, service environments of electrophotographic image forming apparatus are becoming more diverse than ever. Accordingly, it has become important to provide a developer carrying member that can stably provide toners with triboelectric charges over a long period of time even in various environments. Japanese Patent Application Laid-open No. 2001-312136 discloses a toner carrying member having a surface layer containing a quaternary-ammonium-containing copolymer. Then it discloses that such a toner carrying member can provide toners with superior negative chargeability, can prevent after-images from occurring and can remedy any fogging on electrophotographic images.
The present inventors have made studies on the above toner carrying member. As the result, they have realized that it has not still any sufficient performance in providing toners with triboelectric charges in an environment of high humidity. They have also realized that there is room for improvement also about charge-providing performance to a toner standing immediately after an electrophotographic image forming apparatus having been left to stand stopped over a long period of time is again operated. Further, it is preferable for the surface of a developer carrying member to have an appropriate conductivity so that the toner can be prevented from being charged in excess (undergoing charge-up) to come to stick to the surface of the developer carrying member because of mirror force. In order to obtain a developer carrying member which exhibits stable performance in various environments, it is important to make the developer carrying member have these properties in a well-balanced state.